In recent years, a heat ray shielding glass has received widespread attention for improving comfortableness and cooling efficiency in the interior of a room or a vehicle. However, the heat ray shielding glass of a type produced by forming a conductive film on a glass surface is not recommended when required to be able to transmit radio waves having wavelength ranges applied to cellular phone, TV, radio, ITS and the like.
Against the above background, studies have been made on a heat ray shielding glass produced in such a manner as to apply a treating agent obtained by mixing conductive ultrafine particles and a binder component to a glass surface thereby forming a heat ray shielding film. Examples of the treating agent, disclosed in Patent Documents 1 to 4, are produced by mixing ITO fine powder with a binder component formed of alkoxide of Si, Al, Zr, Ti or the like or formed of an organic resin, with which a substrate having a heat ray cutoff effect is obtained.    Patent Document 1: Japanese Patent Provisional Publication No. 07-070482    Patent Document 2: Japanese Patent Provisional Publication No. 08-041441    Patent Document 3: Japanese Patent Provisional Publication No. 2003-064308    Patent Document 4: Japanese Patent Provisional Publication No. 2003-055603